JP3837452B2 - Magnetic sensor - Google Patents

Description

[0001]
The present invention relates to a magnetic sensor used for a control element of a brushless motor.
[0002]
[Prior art]
Magnetic sensors, typified by semiconductor Hall elements, are one of the most important sensors in the fields of household appliances and industrial machinery as control elements in brushless motors. Development is desired. Since the sensitivity of semiconductor magnetic sensors depends on the mobility of electrons in semiconductors, attempts have recently been made to use cold cathode solid-state vacuum devices as magnetic sensors based on the principle of field emission as a measure to improve sensitivity. It has been broken. In addition, it is said that this device can be used at high temperatures and in radioactive environments, and expansion of the application range can be expected.
A typical example of such an apparatus is shown in FIG. A vertical field emission type emitter electrode 1 provided on an insulating or semi-insulating substrate 5 for emitting electrons, and the number of electrons emitted from the emitter electrode 1, that is, for controlling an emitter current. A gate electrode 2, a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1, and an anode electrode 3 for collecting electrons emitted from the emitter electrode 1. Note that element fabrication is performed using a semiconductor process.
[0003]
[Problems to be solved by the invention]
Such a magnetic sensor satisfies the function because the electrodes between the divided anodes are insulated. However, when actually used, the insulation between the anodes decreases. This is presumably because the electron beam modifies the surface of the insulating layer. When the insulation between the anodes decreases, the position where the electron beam reaches, that is, the separation of the current flowing into each anode electrode becomes inaccurate, the accuracy of the sensor decreases, the reliability is reduced, and the application range is narrowed. .
In addition, the magnetic sensor as described above detects the position deflected by the externally applied magnetic field and obtains information on the magnetic field. However, since a gap is necessary for insulation between the divided anode electrodes, The beam avoids the gap and flows only into the divided anode electrode. At this time, even if the position of the electron beam fluctuates due to the magnetic field, a phenomenon occurs in which the anode electrode into which electrons flow does not change until a certain amount of movement occurs. Means that. Therefore, the accuracy of the sensor is lowered, and the application range is narrowed.
Therefore, a first object of the present invention is to provide a magnetic sensor with improved reliability and a wide application range by removing the divided insulating layer between the anode electrodes.
A second object of the present invention is to provide a magnetic sensor having a wide application range by improving the accuracy by forming auxiliary anode electrodes having the same potential between the divided anode electrodes.
[0004]
[Means for Solving the Problems]
In order to achieve the first object, a magnetic sensor according to the present invention includes a field emission type emitter electrode arranged so as to emit a linear electron beam in a vacuum package, and an emitter electrode. A gate electrode for controlling the number of emitted electrons, an anode electrode for collecting electrons of the electron beam provided on a substrate via an insulating layer and collecting the electrons, and a deflection electrode for deflecting the electron beam A magnetic sensor for detecting the intensity of the external magnetic field based on a change in the number of electrons incident on the anode electrode due to the external magnetic field to be measured, and the insulating layer between the divided anode electrodes is removed. It is characterized by that.
According to the present invention, since the insulating layer between the divided anode electrodes is removed, the current distribution can be accurately understood, so that the reliability of the magnetic sensor is improved.
In order to achieve the second object, the magnetic sensor further includes an auxiliary anode electrode having the same potential between the divided anode electrodes.
By providing this auxiliary anode electrode, the electron beam arrival position fluctuates only by application of an external magnetic field, so that the accuracy is improved without the output being stepped.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an enlarged cross-sectional view of the vicinity of an anode electrode portion for explaining a first embodiment of the present invention. The appearance is almost the same as that of FIG.
The magnetic sensor of this embodiment includes a field emission type emitter electrode 1 provided for emitting electrons, a gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current, It comprises an anode electrode 3 for collecting electrons emitted from the emitter electrode 1 and a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1. These components are respectively disposed inside the package 8. The deflection electrode 4 is arranged in four equal portions of 90 degrees with the emitter electrode 1 as the center. Note that the same potential is applied to these deflection electrodes 4. Further, the anode electrode 3 is divided into four parts at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the electron beam deflected in a cross shape to the anode electrode 3 can be determined. An equipotential shielding electrode 7 is provided on the outer periphery of these structures. This is because the conductor is applied to the inner wall of the package 8 and is effective in preventing the danger that the trajectory of electrons is affected by the electric field outside the sensor and bent regardless of the external magnetic field B.
[0006]
All the electrodes described above are arranged radially and symmetrically from the center of the cross-shaped electron beam so as not to give anisotropy to the electron trajectory.
Here, the present embodiment will be described in more detail using a cross-sectional view of the anode electrode 3. At this time, the emitter element that emits electrons is positioned above the figure. In the conventional structure as shown in FIG. 2, the anode electrodes 31 and 32 divided by the insulation deterioration of the exposed portion of the insulating layer 6 become electrically common, and the current cannot be accurately divided and measured. Therefore, the exposed portion is etched with buffered hydrofluoric acid and the insulating layer 6 is divided into portions 61 and 62 as shown in FIG. It becomes like this. Further, it is preferable to perform over-etching because deterioration of the insulating layer can be further prevented.
[0007]
FIG. 3 is an enlarged cross-sectional view of the vicinity of the anode electrode portion for explaining the second embodiment of the present invention. In the figure, the emitter element is positioned below. The external appearance is substantially the same as that of the conventional example shown in FIG. 5, and the configuration of the magnetic sensor is substantially the same as that of the first embodiment.
Here, in the present embodiment, the substrate 9 is an auxiliary anode electrode, and is connected to a wiring led out from each divided anode electrode 3 through the current detection mechanism 11 and connected to the voltage application device 12.
Here, in the structure in which a voltage is simply applied to the anode electrode 3 as shown in FIG. 4, the movement of the electron beam by the external magnetic field is stepped by the gap 10. Therefore, as shown in FIG. 3, the substrate 9 is connected to the wiring led out from the divided anode electrodes 31 and 32 through the current detection mechanism 11 and connected to the voltage application device 12, so that the electron beam arrival position is an external magnetic field. Since it fluctuates only by application, the output is not stepped and the accuracy is improved.
[0008]
【The invention's effect】
As described above, according to the present invention, by removing the insulating layer between the divided anode electrodes, since the current distribution can be accurately understood, the reliability of the magnetic sensor is improved and the application is improved. A magnetic sensor having a wide range can be provided.
Also, by forming an auxiliary anode electrode having the same potential between the divided anode electrodes, the electron beam arrival position fluctuates only by the application of an external magnetic field, so that the output is not stepped and the accuracy is improved. Thus, it is possible to provide a magnetic sensor with a wide application range.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of an anode portion for explaining a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of an anode portion of a conventional magnetic sensor.
FIG. 3 is an enlarged cross-sectional view of an anode portion illustrating a second embodiment of the present invention, with wiring and electric circuit equipment added thereto.
FIG. 4 is an enlarged cross-sectional view of an anode part of the magnetic sensor of the present invention, with wiring and electric circuit equipment added thereto.
FIG. 5 is a schematic view showing the appearance of a conventional magnetic sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Emitter electrode 2 Gate electrode 3, 31, 32 Anode electrode 4 Deflection electrode 5 Substrate 6, 61, 62 Insulating layer 7 Shielding electrode 8 Package 9 Substrate 10 Gap 11 Current detection mechanism 12 Voltage application apparatus

Claims (3)

A field emission type emitter electrode arranged so as to emit a linear electron beam in a vacuum package inside, a gate electrode for controlling the number of electrons emitted from the emitter electrode, and an insulating layer on the substrate Electrons incident on the anode electrode by an external magnetic field to be measured, comprising an anode electrode that collects electrons of the electron beam that are divided into at least two via a deflection electrode that deflects the electron beam In a magnetic sensor for detecting the intensity of the external magnetic field based on the number changing,
2. A magnetic sensor according to claim 1, wherein an insulating layer between the divided anode electrodes is removed. The magnetic sensor according to claim 1, wherein an auxiliary anode electrode having the same potential is provided in the vicinity of the anode electrode. The magnetic sensor according to claim 2, wherein the auxiliary anode electrode is a substrate constituting a substrate that holds the anode electrode.

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